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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Desenvolvimento e efeito da concentração atmosférica de CO2 e da temperatura em plântulas juvenis de Hymenaea courbaril L., jatobá / Development and atmospheric CO2 concentration and temperature responses in platlets of Hymenaea courbaril L., jatobá

Mayorga, Adriana Yepes 09 December 2010 (has links)
O enriquecimento da atmosfera com CO2, produto principalmente das atividades humanas, e a consequênte elevação na temperatura ambiente têm se revelado como importantes fatores que afetam a produtividade das plantas. Hymenaea courbaril L. é uma espécie classificada como secundária tardia no processo de sucessão, de reconhecida importância ecológica por sua ampla distribuição ao longo das Américas. Esta árvore tem sido usada como planta modelo no estudo da mobilização de carboidratos de reserva de parede celular de cotilédones, no estudo das respostas de espécies do Neotrópico às elevadas concentrações de CO2, entre outras pesquisas. É conhecido que em jatobá a mobilização de XG de reserva é conduzida primeiramente às folhas em desenvolvimento. Às elevadas temperaturas favorecem o processo de mobilização. Também é sabido que as elevadas concentrações de CO2 diminuem a mobilização de XG dos cotilédones na fase de pós-germinação. O enfoque deste trabalho foi direcionado ao estudo do desenvolvimento inicial de plantas de jatobá e à compreensão dos processos fisiológicos e do metabolismo de carbono envolvidos nas respostas de plantas juvenis às elevadas concentrações de CO2 e à eT. Com esta pesquisa foi evidenciado que estes fatores se associam sinergicamente e favorecem o desenvolvimento de plantas juvenis de jatobá, acelerando o amadurecimento das folhas de enverdecimento tardio através de um maior e mais rápido acúmulo de clorofilas. Tal interação também parece anular a amortização da mobilização de XG e a aclimatação da fotossíntese, promovidos pelas eCO2. No presente estudo também foi evidenciado que as elevadas concentrações de CO2 favorecem as taxas de assimilação de CO2 e à produção de carboidratos não estruturais, como amido. As elevadas temperaturas aceleram o metabolismo das plantas de jatobá, sendo que o aumento no metabolismo depende do conteúdo de carboidratos. As eT favorecem a síntese de Sac, diminuem a produção de amido, portanto, diminuem a razão Amido/Sac à noite. A estratégia metabólica de jatobá reduziria a sensação por parte da hexoquinase do fluxo de hexoses, com o que se atenuaria o abatimento da síntese de enzimas da fotossíntese (aclimatação da fotossíntese). O desenvolvimento inicial de plantas de jatobá permitiu identificar duas fases de crescimento, que estão determinadas pelas suas fontes e reservas de carbono. A primeira fase é de crescimento linear, e conta com os carboidratos produto da mobilização de XG, a fotossíntese e um enorme armazenamento de amido no caule, este último usado possivelmente como fonte complementaria de carbono para a planta até o completo amadurecimento do sistema fotossintetizante. A segunda fase é de estabilização do crescimento, uma vez que são esgotadas as reservas de amido do caule. Neste ponto, a força do dreno de crescimento diminui e aumenta o acúmulo de amido nas folhas completamente expandidas. Considerando-se as estratégias adaptativas de jatobá, em ausência de estresse hídrico, as condições ambientais de e CO2 até 760ppm e eT até 3°C promovem o crescimento de plantas juvenis de H. courbaril. / The continuous rise in anthropogenic CO2 concentration has the potential to lead to an approximate 3°C increase in temperature worldwide and these is thought as being important factors that affect the plants productivity and distribution. Hymenaea courbaril L., jatobá, is a late-successional species that is recognized by its ecological importance and by their distribution from central America to the south of Brazil. This plant species has been used as a model for the studies of cell wall storage carbohydrates mobilization, as well as for the studies of Neotropic species responses to enrichment CO2 atmosphere. It is known that XG mobilization products are driven primarily to expanding leaves. Elevated temperatures promote this mobilization process. In the present work, he initial development of seedlings of Hymenaea courbaril was investigated in order to understand aspects of physiological bevavior and carbon metabolism under elevated CO2 concentrations (e CO2) and/or elevated temperature (eT, +3°C). The results showed that the e CO2 and eT, when associated, actively improved H. courbaril L. young plants development, promoting the maturation of its delayed greening leaves with a higher and a faster chlorophyll accumulation. Such interaction seems to block the reduction of XG mobilization and the photosynthesis acclimation, previously observed to be promoted by the elevated CO2 atmosphere. It was observed that eCO2 increases net assimilation CO2 rates and the non structural carbohydrates production, like starch. Elevated temperatures improved the metabolism in general and this seems to depend on the carbohydrates status. Elevated temperatures enhanced the sucrose synthesis, diminished the starch production, and the starch/sucrose ratio during the night. The metabolic features observed for Hymenaea courbaril are likely to be associated he sugar sensing mechanism, which reduces the photosynthetic enzymes synthesis reduction (photosynthesis acclimation). The jatobas initial development showed two phases determined by its storage compounds in the cotyledons. The first is a linear growth period during which XG mobilization, photosynthesis and a high starch level is stored in the stem, the latter possibly used as a supplementary carbon source until photosynthesis is fully established. The second phase is growth stabilization, once the stem starch reserves are utilized. At that point, the growth sink forces diminish and consequently an increased concentration of starch is obseved in the completed expanded leaves. Considering those strategies, without water stress, the conditions of elevated CO2 and elevated temperature promote growth of young H. courbaril plants.
2

Desenvolvimento e efeito da concentração atmosférica de CO2 e da temperatura em plântulas juvenis de Hymenaea courbaril L., jatobá / Development and atmospheric CO2 concentration and temperature responses in platlets of Hymenaea courbaril L., jatobá

Adriana Yepes Mayorga 09 December 2010 (has links)
O enriquecimento da atmosfera com CO2, produto principalmente das atividades humanas, e a consequênte elevação na temperatura ambiente têm se revelado como importantes fatores que afetam a produtividade das plantas. Hymenaea courbaril L. é uma espécie classificada como secundária tardia no processo de sucessão, de reconhecida importância ecológica por sua ampla distribuição ao longo das Américas. Esta árvore tem sido usada como planta modelo no estudo da mobilização de carboidratos de reserva de parede celular de cotilédones, no estudo das respostas de espécies do Neotrópico às elevadas concentrações de CO2, entre outras pesquisas. É conhecido que em jatobá a mobilização de XG de reserva é conduzida primeiramente às folhas em desenvolvimento. Às elevadas temperaturas favorecem o processo de mobilização. Também é sabido que as elevadas concentrações de CO2 diminuem a mobilização de XG dos cotilédones na fase de pós-germinação. O enfoque deste trabalho foi direcionado ao estudo do desenvolvimento inicial de plantas de jatobá e à compreensão dos processos fisiológicos e do metabolismo de carbono envolvidos nas respostas de plantas juvenis às elevadas concentrações de CO2 e à eT. Com esta pesquisa foi evidenciado que estes fatores se associam sinergicamente e favorecem o desenvolvimento de plantas juvenis de jatobá, acelerando o amadurecimento das folhas de enverdecimento tardio através de um maior e mais rápido acúmulo de clorofilas. Tal interação também parece anular a amortização da mobilização de XG e a aclimatação da fotossíntese, promovidos pelas eCO2. No presente estudo também foi evidenciado que as elevadas concentrações de CO2 favorecem as taxas de assimilação de CO2 e à produção de carboidratos não estruturais, como amido. As elevadas temperaturas aceleram o metabolismo das plantas de jatobá, sendo que o aumento no metabolismo depende do conteúdo de carboidratos. As eT favorecem a síntese de Sac, diminuem a produção de amido, portanto, diminuem a razão Amido/Sac à noite. A estratégia metabólica de jatobá reduziria a sensação por parte da hexoquinase do fluxo de hexoses, com o que se atenuaria o abatimento da síntese de enzimas da fotossíntese (aclimatação da fotossíntese). O desenvolvimento inicial de plantas de jatobá permitiu identificar duas fases de crescimento, que estão determinadas pelas suas fontes e reservas de carbono. A primeira fase é de crescimento linear, e conta com os carboidratos produto da mobilização de XG, a fotossíntese e um enorme armazenamento de amido no caule, este último usado possivelmente como fonte complementaria de carbono para a planta até o completo amadurecimento do sistema fotossintetizante. A segunda fase é de estabilização do crescimento, uma vez que são esgotadas as reservas de amido do caule. Neste ponto, a força do dreno de crescimento diminui e aumenta o acúmulo de amido nas folhas completamente expandidas. Considerando-se as estratégias adaptativas de jatobá, em ausência de estresse hídrico, as condições ambientais de e CO2 até 760ppm e eT até 3°C promovem o crescimento de plantas juvenis de H. courbaril. / The continuous rise in anthropogenic CO2 concentration has the potential to lead to an approximate 3°C increase in temperature worldwide and these is thought as being important factors that affect the plants productivity and distribution. Hymenaea courbaril L., jatobá, is a late-successional species that is recognized by its ecological importance and by their distribution from central America to the south of Brazil. This plant species has been used as a model for the studies of cell wall storage carbohydrates mobilization, as well as for the studies of Neotropic species responses to enrichment CO2 atmosphere. It is known that XG mobilization products are driven primarily to expanding leaves. Elevated temperatures promote this mobilization process. In the present work, he initial development of seedlings of Hymenaea courbaril was investigated in order to understand aspects of physiological bevavior and carbon metabolism under elevated CO2 concentrations (e CO2) and/or elevated temperature (eT, +3°C). The results showed that the e CO2 and eT, when associated, actively improved H. courbaril L. young plants development, promoting the maturation of its delayed greening leaves with a higher and a faster chlorophyll accumulation. Such interaction seems to block the reduction of XG mobilization and the photosynthesis acclimation, previously observed to be promoted by the elevated CO2 atmosphere. It was observed that eCO2 increases net assimilation CO2 rates and the non structural carbohydrates production, like starch. Elevated temperatures improved the metabolism in general and this seems to depend on the carbohydrates status. Elevated temperatures enhanced the sucrose synthesis, diminished the starch production, and the starch/sucrose ratio during the night. The metabolic features observed for Hymenaea courbaril are likely to be associated he sugar sensing mechanism, which reduces the photosynthetic enzymes synthesis reduction (photosynthesis acclimation). The jatobas initial development showed two phases determined by its storage compounds in the cotyledons. The first is a linear growth period during which XG mobilization, photosynthesis and a high starch level is stored in the stem, the latter possibly used as a supplementary carbon source until photosynthesis is fully established. The second phase is growth stabilization, once the stem starch reserves are utilized. At that point, the growth sink forces diminish and consequently an increased concentration of starch is obseved in the completed expanded leaves. Considering those strategies, without water stress, the conditions of elevated CO2 and elevated temperature promote growth of young H. courbaril plants.
3

Vliv zvýšené koncentrace oxidu uhličitého a dusíkatého hnojení na obsah proteinů gluteninové a gliadinové frakce u ozimé pšenice / Impact of elevated carbon dioxide concentration and nitrogen nutrition on protein content of glutenin and gliadin fraction in winter wheat

Chadimová, Klára January 2016 (has links)
The present study investigates effects of elevated atmospheric carbon dioxide concentration, different nitrogen fertilization levels, drought and UV radiation on protein content of wheat gluten fractions glutenins and gliadins. Winter wheat cultivar Bohemia was grown under ambient CO2 concentration (AC; 400 mol CO2.mol-1) and elevated CO2 concentration (EC; 700 mol CO2.mol-1). Half of the samples was fertilized with 200 kg N.ha-1 (N+) and the other part stayed unfertilized (N–). Other environmental factors were UV radiation exclusion (UV–, UV+) and drought (DRY, WET). Gliadins were separated by A-PAGE, glutenins by SDS-PAGE. Proteins were quantified by computer densitometry. Nitrogen fertilization caused an significat increase of gliadins and glutenins. While some gliadins subfractions were significantly lowered by drought, HMW glutenin subunits showed significant increase. UV radiation exclusion resulted in significant decrease of some gliadin subfractions and glutenin subunits. CO2 enrichment caused significant increase of glutenin subfractions HMW 1 and 2, while gliadin subfractions -5 1 and 1 were significantly decreased by elevated CO2 concentration.
4

Predicting Indoor Carbon Dioxide Concentration using Online Machine Learning : Adaptive ventilation control for exhibition halls

Carlsson, Filip, Egerhag, Edvin January 2022 (has links)
A problem that exhibition halls have is the balance between having good indoor air quality andminimizing energy waste due to the naturally slow decrease of CO2 concentration, which causes Heat-ing, Ventilation and Air-Conditioning systems to keep ventilating empty halls when occupants have leftthe vicinity. Several studies have been made on the topic of CO2 prediction and occupancy predictionbased on CO2 for smaller spaces such as offices and schools. However, few studies have been madefor bigger venues where a larger group of people gather. An online machine learning model using theRiver library was developed to tackle this problem by predicting the CO2 ahead of time. Five datasetswere used for training and predicting, three with real data and two with simulated data. The resultsfrom this model was compared with three already developed traditional models in order to evaluate theperformance of an online machine learning model compared to traditional models. The online machinelearning model was successful in predicting CO2 one hour ahead of time considerably faster than thetraditional models, achieving a r2 score of up to 0.95.
5

Estimativa da carbonatação natural de materiais cimentícios a partir de ensaios acelerados e de modelos de predição / Estimate of natural carbonation of cement materials based on accelerated tests and prediction models

Pauletti, Cristiane January 2009 (has links)
A carbonatação, fenômeno físico-químico de reação entre o dióxido de carbono da atmosfera e os produtos da hidratação do cimento, reduz a alcalinidade do concreto, destruindo a película passivadora que envolve o aço, podendo dar condições para a iniciação da corrosão das armaduras. Devido ao tempo requerido para que a reação ocorra em condições naturais, são utilizados ensaios acelerados. No entanto, não há padronização para estes ensaios e existe a dificuldade de se transpor os resultados dessas pesquisas para as condições reais. Este trabalho tem por objetivo estimar a carbonatação natural a partir de ensaios acelerados e de modelos de predição, avaliando possíveis distorções que possam ser causadas pelo processo de aceleração, como pela intervenção dos parâmetros que constituem os modelos, através da comparação com os resultados experimentais. Foram realizados ensaios de carbonatação natural e acelerada, calculados os coeficientes de aceleração a partir dos dados experimentais, e utilizados dois modelos de predição, sendo um complexo e outro simplificado. Para a parte experimental foram empregadas argamassas preparadas com dois tipos de cimento (CP I-S e tipo CP IV) e três relações água/cimento (0,40, 0,55 e 0,70). Para as amostras dos ensaios acelerados de carbonatação foram utilizados dois tempos de cura (7 e 28 dias), dois tipos de precondicionamento (em sala climatizada e conforme recomendações da RILEM) e, dois percentuais de dióxido de carbono (6% e 100% de CO2). Para os ensaios naturais foram adotados três tempos de cura (7, 14 e 28 dias) e três ambientes de exposição ao CO2 atmosférico, sendo um deles um ambiente climatizado (20°C e UR=70%), protegido das intempéries e outros dois externos, não abrigados das chuvas. Os resultados obtidos indicam que o comportamento das amostras precondicionadas em sala climatizada e carbonatadas com 6% de CO2 são as que mais se assemelham às condições naturais de ensaio. O modelo complexo de carbonatação pode substituir os ensaios de carbonatação, mas exige muitos parâmetros de entrada, difíceis de serem medidos e, portanto, difícil de ser utilizado. O modelo simplificado representou bem os resultados acelerados e naturais e foi adaptado para o caso de cimentos pozolânicos. / Carbonation, a physicochemical phenomenon with a reaction between atmospheric carbon dioxide and cement hydration products, reduces alkalinity in concrete, and can destroy the passivating film that envelops steel, creating the conditions to begin framework corrosion. Accelerated tests are used due to the time needed for the reaction to occur under natural conditions. However these tests are not standardized and it is difficult to transpose the results of these research studies to real-life conditions. The purpose of this work is to estimate natural carbonation based on accelerated tests and prediction models, verifying whether the tendencies of the natural test are maintained in the accelerated tests and how the parameters that constitute the models intervene in the response, as compared to the experimental results. Natural and accelerated carbonation tests were performed, the acceleration coefficients calculated based on experimental data, and two prediction models were used, one of them complex and the other simplified. For the experimental part, cement mortars prepared with two types of cement (CP I-S and type CP IV) were used, and three water/cement ratios (0.40, 0.55 and 0.70). For the samples of the accelerated carbonation tests, two curing times were used (7 and 28 days), two types of pre-conditioning (in an air conditioned room and according to recommendations from RILEM), and two percentages of carbon dioxide (6% and 100% of CO2). Three curing times (7, 14 and 28 days) were adopted for the natural tests, and three environments of exposure to atmospheric CO2, one of them an air conditioned environment (20°C and UR=70%), protected from the weather, and two other external ones not sheltered from the rain. The results obtained indicate that the behavior of the pre-conditioned samples in an air conditioned room, and carbonated with 6% of CO2 is most similar to the natural testing conditions. The complex carbonation model tested at work can replace the carbonation tests, but requires many input parameters that are difficult to measure, and therefore complicated to use. The simplified carbonation model used provided a good representation of the carbonation results observed in the experimental tests and was adapted to the case of pozzolanic cements.
6

Nouvelle technologie de concentration de CO2 intégrée à la cimenterie : étude d'un nouveau procédé de décarbonatation / A new CO2 concentration technology integrated into cement plant : study of a new decarbonation process

Wahl, Sébastien 25 January 2018 (has links)
Cette étude s’inscrit dans le cadre du développement d’une nouvelle technologie de concentration du CO2 intégrée à la cimenterie. Le principe de cette technologie repose sur une décarbonatation de la matière crue par contact avec un solide caloporteur dans un procédé innovant qui conduit à un dégagement de CO2 pur à haute température. Ce CO2 pourra ensuite être stocké dans le sous-sol ou valorisé chimiquement. L’objectif de ce travail est d’étudier la décarbonation du cru dans les conditions opératoires qui simulent le plus fidèlement possible la nouvelle unité industrielle. D’abord, la cinétique de décarbonation est étudiée en thermobalance sur des échantillons de poudre de CaCO3 pur qui est le composé majoritaire du cru. Les résultats conduisent à une meilleure compréhension des phénomènes qui pilotent la réaction ainsi qu’à l’élaboration des lois cinétiques permettant de prédire l’effet de la température entre 600 °C et 930 °C, et de la pression partielle de CO2 entre 0 atm et 1 atm sur l’avancement de la réaction. Ensuite, les interactions pouvant se produire entre le CaCO3 et les autres solides qui composent un cru industriel, lors de sa calcination sous atmosphère de CO2 pur, sont étudiées sur le plan cinétique (thermobalance), thermodynamique (simulations) et morphologique (DRX et DRX in situ). Enfin, dans le but de simuler la décarbonatation du cru et son élutriation dans le procédé réel, et en particulier dans la partie basse du nouveau calcinateur, un pilote fonctionnant à chaud a été réalisé au cours de ce travail. Il permet d’effectuer la décarbonatation du cru alimenté en discontinu et en continu dans un lit de média fluidisé (clinker ou olivine). Ont été examinées les influences de la température, de la vitesse de gaz, du débit de solide et de la nature du gaz de fluidisation (CO2 pur ou mélange air/CO2) sur les phénomènes hydrodynamiques (élutriation, accumulation, temps de séjour …), les interactions cru-média et le degré d’avancement de la réaction de décarbonatation. / This study concerns a new CO2 concentration technology integrated into the cement plant. This technology consists in the raw mix decarbonation, induced by its contact with a solid medium in charge of the heat transfer, in an innovative process leading to the emission of pure CO2 at high temperature. This pure gas may be stored underground or used as chemical reactant. This work consists in the study of the decarbonation reaction of the raw mix in operating conditions that are similar to the ones of the new industrial unit. First, the decarbonation kinetics is studied by thermogravimetric analysis on pure CaCO3 powder samples. CaCO3 is the main component of the raw mix. The results led to a better comprehension of the phenomena driving the reaction kinetics and to the determination of kinetic laws in good agreement with the data obtained between 600 °C and 930 °C, and for a partial pressure of CO2 between 0 atm and 1 atm. Then, the interactions between the CaCO3 and the other solids in an industrial raw mix, occurring during its calcination in pure CO2 atmosphere, are studied kinetically (TGA), thermodynamically (simulations) and morphologically (XRD and in situ XRD). Eventually, an experimental device working at high temperatures was built for this study in order to simulate the decarbonation reaction of the raw mix and its elutriation in the real process. This device allows calcining the raw mix in a fluidized bed of media (clinker or olivine). The influences of the fluidized bed temperature, the fluidizing gas velocity, the solid feed rate and the fluidizing gas composition (pure CO2 or air/CO2 mixes) on the hydrodynamic phenomena (elutriation, accumulation, residence time …) , the raw mix-media interactions and the conversion degree are studied.
7

Estimativa da carbonatação natural de materiais cimentícios a partir de ensaios acelerados e de modelos de predição / Estimate of natural carbonation of cement materials based on accelerated tests and prediction models

Pauletti, Cristiane January 2009 (has links)
A carbonatação, fenômeno físico-químico de reação entre o dióxido de carbono da atmosfera e os produtos da hidratação do cimento, reduz a alcalinidade do concreto, destruindo a película passivadora que envolve o aço, podendo dar condições para a iniciação da corrosão das armaduras. Devido ao tempo requerido para que a reação ocorra em condições naturais, são utilizados ensaios acelerados. No entanto, não há padronização para estes ensaios e existe a dificuldade de se transpor os resultados dessas pesquisas para as condições reais. Este trabalho tem por objetivo estimar a carbonatação natural a partir de ensaios acelerados e de modelos de predição, avaliando possíveis distorções que possam ser causadas pelo processo de aceleração, como pela intervenção dos parâmetros que constituem os modelos, através da comparação com os resultados experimentais. Foram realizados ensaios de carbonatação natural e acelerada, calculados os coeficientes de aceleração a partir dos dados experimentais, e utilizados dois modelos de predição, sendo um complexo e outro simplificado. Para a parte experimental foram empregadas argamassas preparadas com dois tipos de cimento (CP I-S e tipo CP IV) e três relações água/cimento (0,40, 0,55 e 0,70). Para as amostras dos ensaios acelerados de carbonatação foram utilizados dois tempos de cura (7 e 28 dias), dois tipos de precondicionamento (em sala climatizada e conforme recomendações da RILEM) e, dois percentuais de dióxido de carbono (6% e 100% de CO2). Para os ensaios naturais foram adotados três tempos de cura (7, 14 e 28 dias) e três ambientes de exposição ao CO2 atmosférico, sendo um deles um ambiente climatizado (20°C e UR=70%), protegido das intempéries e outros dois externos, não abrigados das chuvas. Os resultados obtidos indicam que o comportamento das amostras precondicionadas em sala climatizada e carbonatadas com 6% de CO2 são as que mais se assemelham às condições naturais de ensaio. O modelo complexo de carbonatação pode substituir os ensaios de carbonatação, mas exige muitos parâmetros de entrada, difíceis de serem medidos e, portanto, difícil de ser utilizado. O modelo simplificado representou bem os resultados acelerados e naturais e foi adaptado para o caso de cimentos pozolânicos. / Carbonation, a physicochemical phenomenon with a reaction between atmospheric carbon dioxide and cement hydration products, reduces alkalinity in concrete, and can destroy the passivating film that envelops steel, creating the conditions to begin framework corrosion. Accelerated tests are used due to the time needed for the reaction to occur under natural conditions. However these tests are not standardized and it is difficult to transpose the results of these research studies to real-life conditions. The purpose of this work is to estimate natural carbonation based on accelerated tests and prediction models, verifying whether the tendencies of the natural test are maintained in the accelerated tests and how the parameters that constitute the models intervene in the response, as compared to the experimental results. Natural and accelerated carbonation tests were performed, the acceleration coefficients calculated based on experimental data, and two prediction models were used, one of them complex and the other simplified. For the experimental part, cement mortars prepared with two types of cement (CP I-S and type CP IV) were used, and three water/cement ratios (0.40, 0.55 and 0.70). For the samples of the accelerated carbonation tests, two curing times were used (7 and 28 days), two types of pre-conditioning (in an air conditioned room and according to recommendations from RILEM), and two percentages of carbon dioxide (6% and 100% of CO2). Three curing times (7, 14 and 28 days) were adopted for the natural tests, and three environments of exposure to atmospheric CO2, one of them an air conditioned environment (20°C and UR=70%), protected from the weather, and two other external ones not sheltered from the rain. The results obtained indicate that the behavior of the pre-conditioned samples in an air conditioned room, and carbonated with 6% of CO2 is most similar to the natural testing conditions. The complex carbonation model tested at work can replace the carbonation tests, but requires many input parameters that are difficult to measure, and therefore complicated to use. The simplified carbonation model used provided a good representation of the carbonation results observed in the experimental tests and was adapted to the case of pozzolanic cements.
8

Estimativa da carbonatação natural de materiais cimentícios a partir de ensaios acelerados e de modelos de predição / Estimate of natural carbonation of cement materials based on accelerated tests and prediction models

Pauletti, Cristiane January 2009 (has links)
A carbonatação, fenômeno físico-químico de reação entre o dióxido de carbono da atmosfera e os produtos da hidratação do cimento, reduz a alcalinidade do concreto, destruindo a película passivadora que envolve o aço, podendo dar condições para a iniciação da corrosão das armaduras. Devido ao tempo requerido para que a reação ocorra em condições naturais, são utilizados ensaios acelerados. No entanto, não há padronização para estes ensaios e existe a dificuldade de se transpor os resultados dessas pesquisas para as condições reais. Este trabalho tem por objetivo estimar a carbonatação natural a partir de ensaios acelerados e de modelos de predição, avaliando possíveis distorções que possam ser causadas pelo processo de aceleração, como pela intervenção dos parâmetros que constituem os modelos, através da comparação com os resultados experimentais. Foram realizados ensaios de carbonatação natural e acelerada, calculados os coeficientes de aceleração a partir dos dados experimentais, e utilizados dois modelos de predição, sendo um complexo e outro simplificado. Para a parte experimental foram empregadas argamassas preparadas com dois tipos de cimento (CP I-S e tipo CP IV) e três relações água/cimento (0,40, 0,55 e 0,70). Para as amostras dos ensaios acelerados de carbonatação foram utilizados dois tempos de cura (7 e 28 dias), dois tipos de precondicionamento (em sala climatizada e conforme recomendações da RILEM) e, dois percentuais de dióxido de carbono (6% e 100% de CO2). Para os ensaios naturais foram adotados três tempos de cura (7, 14 e 28 dias) e três ambientes de exposição ao CO2 atmosférico, sendo um deles um ambiente climatizado (20°C e UR=70%), protegido das intempéries e outros dois externos, não abrigados das chuvas. Os resultados obtidos indicam que o comportamento das amostras precondicionadas em sala climatizada e carbonatadas com 6% de CO2 são as que mais se assemelham às condições naturais de ensaio. O modelo complexo de carbonatação pode substituir os ensaios de carbonatação, mas exige muitos parâmetros de entrada, difíceis de serem medidos e, portanto, difícil de ser utilizado. O modelo simplificado representou bem os resultados acelerados e naturais e foi adaptado para o caso de cimentos pozolânicos. / Carbonation, a physicochemical phenomenon with a reaction between atmospheric carbon dioxide and cement hydration products, reduces alkalinity in concrete, and can destroy the passivating film that envelops steel, creating the conditions to begin framework corrosion. Accelerated tests are used due to the time needed for the reaction to occur under natural conditions. However these tests are not standardized and it is difficult to transpose the results of these research studies to real-life conditions. The purpose of this work is to estimate natural carbonation based on accelerated tests and prediction models, verifying whether the tendencies of the natural test are maintained in the accelerated tests and how the parameters that constitute the models intervene in the response, as compared to the experimental results. Natural and accelerated carbonation tests were performed, the acceleration coefficients calculated based on experimental data, and two prediction models were used, one of them complex and the other simplified. For the experimental part, cement mortars prepared with two types of cement (CP I-S and type CP IV) were used, and three water/cement ratios (0.40, 0.55 and 0.70). For the samples of the accelerated carbonation tests, two curing times were used (7 and 28 days), two types of pre-conditioning (in an air conditioned room and according to recommendations from RILEM), and two percentages of carbon dioxide (6% and 100% of CO2). Three curing times (7, 14 and 28 days) were adopted for the natural tests, and three environments of exposure to atmospheric CO2, one of them an air conditioned environment (20°C and UR=70%), protected from the weather, and two other external ones not sheltered from the rain. The results obtained indicate that the behavior of the pre-conditioned samples in an air conditioned room, and carbonated with 6% of CO2 is most similar to the natural testing conditions. The complex carbonation model tested at work can replace the carbonation tests, but requires many input parameters that are difficult to measure, and therefore complicated to use. The simplified carbonation model used provided a good representation of the carbonation results observed in the experimental tests and was adapted to the case of pozzolanic cements.
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Energeticky úsporná budova kina s galerií / Energy efficient building of cinema and gallery

Kučírek, Pavel January 2022 (has links)
The aim of the master project is to design a new building of the cinema with gallery and to design technical equipment. The building is „L“ shaped, the half of the building is single-storey and the other half is two-storey, there is no basement. The most important rooms are on the ground floor – gallery, cinema, foyer and staff rooms. On the second floor there is projector room, sound engineer room, recording room and other sound adjusting rooms. The vertical loadbearing and non-loadbearing walls are designed from aerated concrete blocks, horizontal structure are cast-in-place reinforced slabs, the roof is flat. There is a reinforced concrete staircase that leads to the second floor, the building is insulated by ETICS. There are 4 HVAC units designed in the building, units are controlled with monitoring and controlling unit, also there are photovoltaics and rainwater storage systems designed. The project and visualizations were made in the ArchiCAD, MS excel, DEK, Halton HIT, AeroCAD software. Experiment validates measured data with mathematical analytics model that I used in 7 theoretical models of ventilator controlling possibilities to achieve energy savings. Re-sults will be compared and assessed.
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Variations in the partial pressure of carbon dioxide within the Indalsälven River system : An analysis of multi-year data of several parameters to get an insight into the functioning of sub-artic river pCO2 spikes.

Cuijpers, David Leon January 2023 (has links)
Climate change has, in recent decades, warmed the climate and changed carbondynamics in land and water systems. For example, temperature and precipitation canchange carbon dynamics and cause largely unknown consequences. This researchuses data from a unique measuring station near Kattestrupeforsen, Jämtland, Sweden, in order to answer the question of how the pCO2 (ppm) concentration of the water in the local area reacts to changes in the factors of air/water temperature, solar irradiation, precipitation, turbidity, water level and water inflow into the area. This was analysed using a visual analysis of the peaks that occur in the pCO2 and a statistical regression analysis of peak pCO2 events and for each yearly quarter as well as for the identified peak events. Moreover, the limited amount of available turbidity data was visually analysed to comprehend how it correlates with the pCO2 values. The results indicate that the turbidity data available has no visible correlation, possibly due to a lack in data. Temperature data appeared to be responsible for some of the variation seen, although likely more as a conditional value. Irradiation and precipitation data gave inconsequent results and are not deemed likely to influence the peaks in pCO2 in the time scale analysed. Water level and streamflow showed the most stable and significant correlation of all parameters analysed, although they remained relatively inconsistentin their ability to explain pCO2 peaks seen. / <p>2024-03-06</p>

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